Ecological protection and restoration system of mountain-river-forest-farmland-lake-grassland: practicing the theory of lucid waters and lush mountains are invaluable assets

China is vast in area, but because the population base is huge, the spatial distribution of available land resources is uneven. With the remarkable improvement of the country's economic power and people's living standard, how to realize the sustainable development of the economy and promote the coordinated development of socio-economy and environmental protection under the limited land and resources has become an urgent problem to be solved. The important concept of “mountains, rivers, forests, farmlands and lakes are a community of life” proposed by President Xi Jinping and the idea of systematic governance have pointed out the direction for solving this development problem. The strategic background of ecological protection and restoration of mountain-river-forest-farmland-lake-grassland (MRFFLG) was analyzed and the guiding ideology, basic principles and systematic design ideas of ecological protection and restoration of MRFFLG explained. The key tasks of ecological protection and restoration of MRFFLG were put forward, including the preparation of restoration plan, the scientific determination of spatial distribution, the optimization and adjustment of the resulting structure and population distribution, carrying out ecological restoration according to local conditions, promoting ecological protection and restoration by multi-departments, and clarifying its technical requirements.